Screw driver bit



FIG. 1 is a perspective view of a screw driver bit, showing my new design;

FIG. 2 is a front end elevational view thereof;

FIG. 3 is a rear end elevational view thereof; and

FIG. 4 is a side elevational view thereof, all other sides being identical. 

The ornamental design for a screw driver bit, as shown and described. 